Mars has a liquid iron alloy core at its center. Using seismic data gathered by the InSight mission, we have made the first observations of seismic waves traveling through Mars’ core. We use the travel times of core-transiting seismic waves, relative to ones which remain in the mantle, to constrain properties of the core and …
Constraints on Martian Core from First Observations of SKS Waves Read More »
Low-velocity layers within the crust can indicate the presence of melt and lithologic differences with implications for crustal composition and formation. Seismic wave conversions and reverberations across the base of the crust or intracrustal discontinuities, analysed using the receiver function method, can be used to constrain crustal layering. This is commonly accomplished by inverting receiver …
Spurious Low Velocity Zones in Joint Inversions of Surface Waves and Receiver Functions Read More »
With collaborators Scott Burdick at Wayne State University and Lauren Waszek at New Mexico State University — both former Maryland postdocs — we just published the first tomographic model of Earth’s inner core in Earth and Planetary Science Letters. Seismic body wave and normal mode analyses have revealed that the inner core is solid, strongly …
We have published a new model of 1D structure of the outer core, parameterized using two different equations of state: Irving_Cottaar_Lekic_2018 Brief highlights: We infer the seismic properties and equation of state of the outer core using Earth’s oscillations We address a longstanding discrepancy between high and low frequency investigations of the outer core Our work …
Graduate students at the University of Maryland Seismology Lab sprung into action following the M4.1 earthquake that struck Dover, Delaware on November 30, 2017. The very next day, they were out in the field, deploying seismometers that would be recording aftershocks for the next 6 weeks. Thank you Erin, Chao, Phillip, Karen, Pete, and Quancheng …
Conversions of shear waves (S) to compressional waves (P), often analyzed as Sp receiver functions, are useful for studying upper mantle layering, and have been used to map upper mantle seismic impedance interfaces in various tectonic settings. Recently, common conversion point stacking of Sp receiver functions has revealed variations of lithospheric thickness across short horizontal …
Things to consider when interpreting Sp receiver functions… Read More »
It is well known, at least among tomographers, that our images of the Earth’s interior are washed out. Lateral variations in seismic velocities are likely to be weaker in our models than in the actual Earth due to explicit and implicit regularization needed to obtain a solution to our mixed-determined inverse problems. As a result, …
The EarthScope project has been described as the Apollo program of the solid Earth community. It has enabled an unprecedented investment in seismic instrumentation, and the creation of a uniform and high-quality network covering the United States. Data collected by this network transformed our ability to image the continent and what lies beneath it. In …
Improvement in P-wave tomography due to EarthScope Read More »
Using depth-dependent clustering analysis of global Vs and Vp tomographic models, we have constructed a new reference model for LLSVP shape and volume. We obtain new, much larger estimates of the volume/mass occupied by LLSVPs—8.0 % ±0.9 (μ ± 1σ) of whole mantle volume and 9.1 % ±1.0 (μ ± 1σ) of whole mantle mass. We also …
REM-3D is a project funded by the National Science Foundation and carried out by Raj Moulik, Ved Lekic, Barbara Romanowicz, and Adam Dziewonski. If you have questions, please do not hesitate to contact us. You might find the answer you are looking for in our new FAQ section. The aim of the project is to develop a three-dimensional …
